Performance enhancement of solar absorption cooling systems using thermal energy storage with phase change materials

Thermal energy storage has been shown to improve the efficiency of solar absorption cooling systems by capturing excess insolation during peak to meet cooling demand in low insolation periods. While water is the most commonly used thermal storage medium in solar cooling applications, the small operating temperature range of solar cooling systems limits its energy density. In contrast, Phase Change Materials maintain a high energy density under limited temperature ranges, and are ideally suited for such applications. Methods to select and size appropriate thermal storage technologies in solar cooling applications vary between studies with no standard methodology being utilized across the literature. Moreover, there is limited quantification of the influence of thermal storage on system performance to motivate the additional capital investment in these systems. This study provides an analytical framework to quantify the benefit of the thermal energy storage. Predictions from the analytical model are compared to the results from a validated transient system simulation. The paper gives an engineering approach for predicting the expected benefit from both water and phase change materials based thermal storage for applications with limited temperature ranges.